In the prior art is is known that the field of integrated optics includes many solid state devices that operate as optical waveguides for optical communication systems--see the publication "Survey of Integrated Optics," S. E. Miller, IEEE Journal of Quantum Electronics, Volume QE-8, No. 2, February 1972, pages 199 - 205. Recently developed thin-film technology has permitted the fabrication of miniature, solid state devices that permit the transfer of optical power from a thin-film structure to an associated optical fiber transmission line--see the I. P. Kaminow, et al, published patent application B 381,985, published Feb. 3, 1976. The present invention is considered to be an improvement over these known prior art devices.